Hi Alex:
With a camera DSLR you have a matrix of bayer, your chip is one color shot,
http://en.wikipedia.org/wiki/Bayer_filter , you are not going to need colors filters, seems to me that it is not recommendable.
For this reason, it would prefer to use the adapter of 2" , and this it can even cause something of Vignetting, but always you will be able to eliminate it, calibrating, with a good series of Flats.
Many greetings
Cesar